studies mentioned in this review. Moreover,
despite the emphasis on carbohydrate in the diet
of most athletes, maintaining 10% (2100 kJ or
500 kcal) of energy intake as protein should not
pose a problem because, if fat intake was
30% (6300 kJ or 1500 kcal), 12.6 MJ (3000 kcal)
would remain, enabling this hypothetical
athlete to consume about 750 g of carbohydrate
(10.7 g · kg–1). This quantity of carbohydrate is
certainly more than sufficient for any carbohy-
drate loading programme.
Inadequate protein intake in active individuals
is most likely to occur in those who have other
pre-existing conditions that interact with the
exercise effect to increase the quantity of dietary
protein required—for example, during periods
of rapid growth, e.g. in adolescents, children,
women who are pregnant, etc.; in situations
where total energy intake is inadequate, e.g.
dieters, those in body mass-restricted activities,
etc.; or in those who do not consume a diet from a
wide variety of food sources, e.g. many adoles-
cents, vegetarians, women, seniors, etc. For some
athletes, insufficient energy intake occurs (and
therefore perhaps protein, as well) because of the
sheer bulk of food and fluids required to main-
tain energy and fluid balance. In such situations,
the use of a liquid meal replacement formula
may be advantageous.
If dietary inadequacies are suspected it is best
to complete a diet analysis (typically a 3–7-day
food record is analysed with commercially avail-
able software) in order to verify that there is
in fact a problem. Unfortunately, in free living
humans these analyses can be grossly inadequate
not only because the subjects are sometimes
given poor instructions but also because some
subjects modify their diet in an attempt to please
the investigator. In addition, use of inadequate
methods to accurately quantify serving size is a
common problem (weigh scales must be used),
as is simply forgetting to record all food con-
sumed. Finally, 3 days may not be representative
of one’s true diet especially if weekends are
excluded (food intake may differ substantially
between week and weekend days) and 7-day
records are not always better because less-
146 nutrition and exercise
motivated subjects can become bored with
the process and, consequently, fail to report accu-
rately. For all these reasons, extreme care must
be used in the interpretation of this kind of
information.
Assuming that care has been taken to obtain an
accurate representation of an individual’s diet
and an insufficient protein intake is found, one
can usually correct the problem with a few minor
adjustments in the individual’s food selections.
This means that, despite the fact that regular
participation in an exercise programme (either
strength or endurance) will apparently increase
protein requirements, special protein supple-
ments (which are considerably more expensive
than food protein per kilogram of protein mass)
are rarely necessary. Further, if it is determined
that it is not possible to consume sufficient
protein in food and a decision is made to use
a supplement, one of the best and most cost-
effective approaches would be to fortify one’s
food with a high-quality, low-cost protein such as
skim milk powder. Finally, there is even less
support for the commonly used practice of
individual amino acid supplementation. Until
such time as it is clear that one or a few individ-
ual amino acids in high dosages are both benefi-
cial and safe, this latter strategy is definitely
contraindicated.Conclusion
After reviewing the literature, it is possible to
make a case that protein needs are elevated
in physically active individuals, apparently to a
greater extent with those actively engaged in
regular strength exercise than with endurance
exercise. The limited available information sug-
gests that the exercise effect on protein needs
may be greater in men than in women. In addi-
tion, the increased protein need is likely greatest
in situations where other factors compound the
exercise effect. However, there is still consider-
able debate regarding the magnitude of this exer-
cise effect on protein requirements. This debate
centres on a variety of methodological concerns
which compromise a significant amount of the